suprathepeg

Here is my dilemma:

Truck won't start.

About 2 weeks ago I drove to work and it ran fine. Then I went to drive home and it ran like crap and kept running like that for about a week. The idle was really lumpy and it wouldn't hold idle. Also when it ran it ran really rich. I pulled the codes and got a code 25 which is a lean reading from the o2 sensor.

Last weekend I replaced the o2 with a new NGK unit I was waiting for good weather to instal and I ensured that there are no leaks in the intake anywhere. This did nothing to improve idle, we unplugged the VAFM and idle improved somewhat, we plugged it back in and the engine died so we assumed the problem was the VAFM

Then last Monday I drove to work and after it just wouldn't start. So Tuesday I had my GF pick up a used VAFM for me and bring it out to me after work so I could replace the apparent broken one and after about 5 minutes of cranking it finally fires and although rough after about 5 minutes of idle it levels out and the next day its running better then ever.

Today I drive to work, all is good. I go to drive home and same story: rough idle, rich mixture and dies at idle . So now I'm pissed.

I get it home and start trouble shooting again. I started it, pulled the VAFM connector off and put it back on and the result is the same as before. So I pulled the codes and this time I get 24,31 and 32 which all point to VAFM. I imagine this is because I pulled the connector off and the VAFM is really fine (hopefully).

I disconnected the negative power from the battery to clear codes, reconnected it and now it won't start at all. It just turns over and over but no fire. I pulled the codes again and all I get is a constant flashing.

I'm thinking it could be something with the ignition or the ECU, anyone please help. What should I start poking at next?

stock87

Have you checked for intake leaks? If there's a big one, the AFM wont be pulled open, no fuel, no start.

all_terrain17

Might as well pull the EFI fuse for a while just for the heck of it...

Wait, nm you reset the battery

thook

That's a bugger of a symptom! Way back when I was repeatedly troubleshooting our '92, I had the same symptoms....only due to a rich condition. It could be a number of things, and I went through those things over and over eventually rebuilding because of the burnt valve. BUT! Even after the rebuild I still had the same symptoms. It wound up being the ECT sensor was bad. You might try that. It's a simple one, discounting the location of the sensor.

Good luck, Supra.

suprathepeg

Remind me again what the ECT sensor is?

thook

Engine coolant temp. sensor.

suprathepeg

aah right. Damn thats gonna suck, its all the way in the back. THook where you getting an error code?

thook

Yep, I was getting a code 26. Same troubleshooting steps for 25.

Do you know of this site?....
http://www.off-road.com/toyota/tech/codes/index.html

This chart coupled with FSM troubleshooting guide, I was able to finally pinpoint the problem. I tried testing the sensor first with an ohm meter, but all that said was that there was continuity. Because I didn't care to follow the other test procedure in the FSM, I switched out the sensor with a spare I had and problem was gone.

It is a very big PITA to get to. I had become so familiar with pulling the plenum (had to do this a number of times dealing with different issues) that I just unbolted it, disconnected the minimum number of components enough to pull it back, and went at it. It really, really was easier mentally and physically than trying to work at it without doing so. On the other hand, if you happen to have a basin wrench that would make it easy to pull. I used one to get my knock sensor out because I didn't have the right sized deep socket on hand.

Basin wrench..
http://www.ehow.com/buy_3841_basin-wrench.html

That being said, it may not be your problem, but if it's never been changed it's worth checking.

And BTW, doesn't a constant flashing mean everything is a-okay? I'm drawing a blank here!